1. Field of the Invention
The present invention relates generally to communications systems and, in particular, to telephone systems. Fraudulent long distance calls have caused multi-billion dollar losses for telephone companies. Many of the fraudulent calls have recognizable patterns which could be detected and controlled if it were possible to intercept the calling information "on the fly". Similarly, if it were possible to catch signal directing information on the fly, then long distance calls could be rerouted when there is a problem with the telephone interchange as originally routed. This rerouting also provides flexibility to the carrier in choosing the routes for their calls.
2. Description of Related Art
In order for a calling party to place a telephone call to a called party, signalling is used to tell the called party that the calling party wishes to communicate. A recent method used to signal across telecommunications networks is known as "Signalling System 7" (SS7) has been standardized by the International Telegraph and Telephone Consultative Committee. Unlike previous technologies which used the same transmission path for the telephone conversation and for signalling across a network to the called party, known as "in-band signalling," SS7 uses separate dedicated transmission paths (SS7 links) to pass all of the required signalling information across the telecommunications network, known as "out-of-band signalling." Imbedded in the data that is sent over these SS7 links is addressing information such as calling party number, called party number, credit card number, originating switch ID, terminating switch ID and routing information among other parameters. Each network device the data passes through is addressed within the data stream and may or may not be modified or additional information inserted into the data packet as it traverses the network.
Signal transfer point (STP) switches can have signal intercept capabilities built-in as can other switches with international transfer capabilities. Such STPs are very expensive and having built-in capabilities only at the switches severely limits flexibility in handling calls. These problems also remain for all of the switches which do not have such built-in capabilities.